Chlorophyll-protein complexes of a marine green alga, Caulerpa cactoides

Abstract

Three main chlorophyll-protein complexes have been resolved by gel electrophoresis from a marine green alga, Caulerpa cactoides, which has a low chlorophyll a/chorophyll b ratio of 1.62. Of the 6 chlorophyll-protein complexes resolved, two are chlorophyll a-proteins related to the reaction centre complex of photosystem 1, one is the chlorophyll a-protein of the presumed reaction centre complex of photosystem 2, and three are chlorophyll a/ b-proteins of the light-harvesting complex. Some 61% of the total chlorophyll was associated with the light-harvesting complex and 23% and 6% with the reaction centre complexes of photosystems 1 and 2, respectively. In contrast to the light-harvesting complexes of higher plants which have equimolar amounts of chlorophylls a and b, the light-harvesting complex of Caulerpa has 1.45 times as much chlorophyll b as chlorophyll a. Variations in the pigment contents of the photosynthetic units of chlorophyll b-containing plants are reflected not only in varying amounts of total chlorophyll associated with each of the three main chlorophyll-protein complexes, but also in the stoichiometric amounts of chlorophyll a and chlorophyll b present in the light-harvesting complexes.